1. Field of the Invention
The present invention relates to a technique for facilitating an assembly property of a motor and enhancing its reliability.
2. Description of the Related Art
FIG. 4 shows a fan motor 1 as an example of equipment using a brushless DC motor. The fan motor 1 has a casing 5 fixed to a center of an air ventilation hole 3 provided in a body 2 by using four bridge portions 4. A PC board (printed circuit board) 6 provided with a drive circuit and a stator 7 are received in the interior of the casing 5. Then, a magnetic field generated by the stator 7 is applied to a magnet 9a of a rotor 9 formed integrally with a fan 8 to thereby cause the fan 8 to drivingly rotate about a shaft 8a passing through the stator 7.
FIGS. 5(A) and 5(B) are a side view and a front view of the stator 7. The stator 7 is provided with four pole portions 7a, 7b, 7c and 7d on which conductive wires are wound to form coils and an insulating structure for an iron core 12 with four pole insulators 10 and 11 molded in resin. Rod-like terminals 13 are press-fitted in three places 7a, 7b and 7c out of the four pole portions of the insulator 11. An end portion of the conductive wire that forms the coil is wound around and soldered to the terminal 13. Furthermore, the tip end portion 13a thereof is soldered to the PC board 6 (FIG. 4). Accordingly, the insulator 11 and the PC board 6 are fixed to each other through the terminal 13. Also, the coil windings and the PC board 6 are caused to be conductive to each other through the terminal 13.
By the way, the stator 7 shown in FIGS. 5(A) and 5(B) has a structure in which the terminal 13 is pressingly inserted and fixed to the insulator 11. For this reason, when the end portion of the conductive wire is wound around and soldered to each terminal 13, if the terminal 13 is subjected to its heat and heated, resin made insulator 11 is also heated and softened. As a result, the terminal 13 is threatened to be removed or tilted. The probability of occurrence of such inconvenience is increased as a result of an increase in temperature of the terminal 13 according to an extension in diameter of the conductive wire accompanied by the increase of heat amount needed for soldering work. Conventionally, in some cases, in order to prevent the occurrence of such inconvenience and to keep a satisfactory easy-assembly property and reliability of the motor, restrictions such as limiting the selection range of the conductive wire is provided in the structure of the motor.
In view of the foregoing problems, an object of the present invention is to facilitate the assembly property and enhance the reliability of a motor without placing restrictions on the structure of the motor.
According to a first aspect of the present invention for the purpose of solving the above problems, there is provided a motor wherein a terminal is inserted into a resin-made insulator for insulating an iron core of a stator, the terminal is fixed to a PC board and these components are received in a casing, characterized in that a high heat-resistant resin is interposed in a press-fitted portion of the terminal to the resin-made insulator.
According to the present invention, the heat-resistant resin suppresses the transfer of heat from the terminal to the resin-made insulator to thereby prevent the resin-made insulator from being softened by receiving the heat from the terminal. Thereby, the terminal is prevented from the xe2x80x9cremovalxe2x80x9d or the xe2x80x9ctiltxe2x80x9d from the resin-made insulator.
According to a second aspect of the present invention, the high heat-resistant resin is applied to the press-fitted portion of the terminal to the resin-made insulator. With such an arrangement, it is possible to fix more positively the high heat-resistant resin and the terminal and to perform simultaneously the press-fitted of the high heat-resistant resin into the resin-made insulator with the press-fitted work of the terminal.
Furthermore, according to a third aspect of the motor of the present invention, a slit is formed at a portion of the resin-made insulator into which the terminal is press-fitted. In case of adopting a layout in which the portion of the resin made insulator into which the terminal is to be press-fitted is located in the vicinity of the outer circumferential end portion of the resin-made insulator, the slit exhibits the effect to replace the thin portion of the resin to prevent the molding defect.
Also, according to a fourth aspect of the present invention, a boss is formed as a portion of the resin-made insulator into which the terminal is press-fitted. With such an arrangement, it is possible to increase the amount of press-fitted (portion to be press-fitted) of the terminal to the resin-made insulator and to prevent more positively the xe2x80x9cremovalxe2x80x9d or xe2x80x9ctiltxe2x80x9d of the terminal from the resin-made insulator.
According to a fifth aspect of the present invention, a rib is provided on the boss. With the provision of the boss, it is possible to reinforce the boss that becomes a base for supporting the terminal and to prevent more positively the xe2x80x9cremovalxe2x80x9d or the xe2x80x9ctiltxe2x80x9d of the terminal from the resin-made insulator.